Harpy eagle hippogryphs grow up quickly, in no small part due to the extensive care they receive from their parents and the other hippogryphs in their rookery. During most years, these hippogryphs are solitary or live only with their chosen mate, but every few years, a large group of five to fifteen related creatures will gather at a traditional nesting site and lay their eggs in a single nest. The adult males take turns incubating the eggs while the females guard the nest and hunt. When the eggs hatch, they all receive attentive care from their parents and the other eagle hippogryphs in the rookery. In the following weeks, they are out of the nest and exploring on their own or play-fighting with each other; a few months later, they are being taught to hunt and fly by their parents. Within a year after they hatch, the youngsters are on their own and large enough to care for themselves. It may take several years for the newly-fledged juveniles to find a suitable partner, and when they do, they will return to the nest site and begin their own families.

No one knows when the first eagle hippogryph came to be, as rocs and minicorns almost never mate in the wild, but the charismatic traits of their offspring have given the eagle hippogryphs their fair share of village tales. The most common one tells of a dark wizard who magically crossed one of the gentlest creatures known, a minicorn, with one of the fiercest, a massive roc, and the resulting offspring was so conflicted about how it should act that it escaped its wizard master and hid deep within Silva forest. According to the legend, it met the spirit of a forest dweller that needed to cross a vast river in order to reach the land of the dead. The newly-made eagle hippogryph helped the spirit on its journey, both carrying it across the river and protecting it within the land of the dead. As a reward for its efforts, the spirit endowed the eagle hippogryph with the power to protect others in the future. This story crosses through many different cultures in one form or another, and as a result, many tombstones are decorated with motifs of eagle hippogryphs as a token of good luck in the next life. Most magi dismiss superstitions about harpy eagle hippogryphs being able to ward off death or Tetzcotal eagle hippogryphs carrying people into the spirit world, but they are well-aware of the healing properties of their feathers and the magical strength that both of these eagles possess.